Process of drying lumber



F. K. FISH, .ln. PROCESS OF DRYING LUMBER.

APPLICATION FILED APR.23. 1919.

Patented Jan. 20, 1920.

2 SHEETSSHEET I.

F. K. FISH, JR-

PROCESS OF DRYING LUMBER.

APPLICATION FILED APR.23. 1919.

1,328,655. Patented Ja11.20,1920.

2 SHEETS-SHEET 2.

avwentoz FREDERICK K. FISH, JR,, OF NEW YORK, N. Y.

PROCESS OF DRYING LUMBER.

Specification of Letters Patent. Patented Jan, 20, 1920,

- Application filed April 23, 1919. Serial No. 292,053.

' To all whom it may concern:

Be it known that I, FREDERICK K. F sn, J12, a cltizen ofthe UnitedStates of America, residing at 2 Stone street, New York.

city, in the county of New York and State of New York, have inventedcertain new and useful Improvements in Processes of Drying Lumber,ofwhich the following is a specification.

The present inventioin is based upon a proper recognition of thephysical characteristics of wood structure, the chemical constituency ofits fluid content, and has for its object the removal from the wood ofthose substances which, under natural con ditions, form the basis of itsdeterioration or destruction, and subsequently drying the wood.

structurally, wood consists of a skeleton of cellulose intermingled withother organic substances. collectively designated as lignin, togetherwith a minor proportion of mineral matter or ash. Li nin, while notfully understood chemically, is closely allied to the cellulose elementof the wood, and since it forms a part of the permanent structure ofthewood, it may, for the purposes of the present invention, be regarded asidentical with the cellulose.

I am aware, that for the obtaining of the objects above set forth, thatwood has been subjected to steam with and without pres sure, thereafterdrying the wood in kilns from which the accumulating moisture iswithdrawn ..,continuously. I have found that by placing wood in asuitable container and surrounding it with a body of live steam underpressure while simultaneously sup plying dry heat to the interior of thecontainer, that a much better and etlicient resuit is obtained, for thereason that the combined action of the dry heat and the live steam underpressure on the lumber is such that, while thesteam prevents the heatfrom too quickly drying the surface of the lumber, a condition whichwould prevent the penetration thereof by the steam, the dry heat raisingthe temperature of the lumber to such a degree as to prevent the condenasatiou of the steam in the cells thereof by its suddenly coming incontact with "the cold condition which. has proven a seriousobjection tothe process heretofore used, when steam, under pressure, is the treatingmedium.

-.It will be found that where wood is subjected to the combined actionof live steam under pressure and dry heat, that the wood piece willbecome heated through and through and the steam and dry heat willpenetrate to the center of the wood piece, the steam thereby coming incontact with the sap globules bursting them. Where dry heat is appliedsimultaneously with the .steam under pressure, the center of the woodpiece will be brought to the same temperature as the surface thereof,causing evaporation from the center outwardly.

If wood is subjectedto a body of live steam under pressure without theaccompanying action of dry heat, the steam, on

being forced into the cells of the wood piece, will become condensedtherein, thereby adding to the already aqueous content of the wood,which will result in materially lengthening the time required for dryingit thereafter. It is a well settled fact that'a comparatively smallamount of heat will maintain a given temperature in a drying chamberwhen the aqueous content of the wood in such. chamber has beenpreviously reduced, as compared with wood from which a portion of theaqueous content has not been previously reduced, so that thedisadvantages of the condensing of the steam within the cells of thewood, thereby doubly loading it with aqueous matter, can be readilyseen.

While if dry heatand live steam under pressure are simultaneously:applied, the wood is kept in a heated condlt on and the steam preventedfrom condensing 1n "the cells of the wood, and since steam has an thecontainer 1, which-is then hermetically the same will be described withreference to the accompanying drawings, in which Figure 1 is avertical,longitudinal section of' a container, suitable for carrying out thefirst step of the process.

Fig. 2 is. a section taken on line ma Fig. 1.

Fig. 3 illustrates diagranm'iatically means for controlling thecondition within the container.

Fig. 4 is a vertical, longitudinal section of a drying chamber.

Fig. 5 is a section taken on line bb Fig. 4.

eferringto the drawings more specifically, reference numeral 1represents a container of construction suitable for containing steamunder pressure, and is provided with a presser plate 2 with adjustingscrews 3 through means of which the charge of wood may be kept underpressure to prevent warping while being treated. It is also providedwith heating coils 4 by which the temperature of the atmosphere or steamwithin the container may be heated to the desired degree; and with pipes5 which are perforated for the purpose of supplying live steam to theinterior of the container when desired. 6 represents a. track to receivethe car or truck upon which the wood is loaded for introduction into thecontainer. 7 is a safety valve. pipe which is provided with valve 9 forcontrolling the pressure within the container 1 at will. 10 is a carupon which wood 11 is loaded for introduction into the container 1. 12represents a boiler for generating steam and is connected to container 1by pipe 13 which is supplied with a suitable va ve 14 for controllingthe flow of steam into container 1.

Referring to Figs. 4 and 5, 15 represents the drying chamber which isprovided with a pressure device 2, 3*, similar in structure to thatemployed in the container 1. 16 are heating pipes preferably located atthe bottom of drying chamber 15 and are for the purpose of introducingdry heat thereinto. 17 is a traclnfor the convenient introduction intodrying chamber 15 of a car load of wood and 18 is a stack which isprovided with damper 19 and is for the purpose of removing from dryingchamber 15 the accumulating moisture from around the wood at will.

In carrying out the process with the apparatus above described, avsuitable charge of wood loaded on a truck is introduced into 8 is anescape closed and steam supplied through the spray pipe 5, and heatsupplied through the operation of pipes 4.

To create the next step, the container 1 is opened and the load of woodis removed therefrom and transferred as rapidly as pos-' sible to thedrying chamber 15, the load beingpreferably covered to minimize loss ofheat during the transfer. Container 1 is now ready to repeat the firststep of the process while the last step is being carried on in thedrying chamber 15, said chamber being already heated is closed upon theload of Wood, the heating pipes 16 are operated sufficiently to keep upa temperature favorable to continuous evaporation of moisture from thewood, and the damper 19 in the stack is opened periodically tocreate adraft or current of air for carrying off the moisture as it accumulates,or may be kept applying dry heat; the final step brings about completedrying under conditions that evaporate remaining moisture at atmosphericpressure in a sufiiciently gradual manner to avoid taking the resin awayfrom the wood structure.

What I claim is:

1. The process of drying lumber, which consists in subjecting the lumberto a body of live steam under pressure, while simultaneously applyingdry heat, then subjecting the lumber to a body of dry heat Whileperiodically removing the accumulating moisture from around the lumber.

2. The process of drying lumber, which consists in subjectingthe'lumberto a body of live steam under pressure while simultaneouslyapplying dry heat, then subjecting the lumber to a body of dry heatuntil dry, keeping the lumber under mechanical pressure during all thesteps of the process. 3. The process of drying lumber, which consists insubjecting the lumber to a body of live steam under pressure whilesimultaneously applying dry heat, then subjecting the lumber to a bodyof dry heat while removing the accumulating moisture fromaround thelumber and keeping the lumber under mechanical pressure until dry. 7

4. The process of treating wood, which consists in producing in aretort-a body of free steam under pressure around the wood, whileapplying a dry heat to the wood, and then subjecting the wood to a dryheat while periodically. removing accumulating mois ture from saidretort.

5. The process of treating Wood, which consists in producing around thewood while in a retort, a body of free steam under pressure, and thentransferring the wood from said retort into an equalizing chamber andthen subjecting thewood to dry heat while removing the accumulatingmoisture from the equalizing chamber.

6. The process of treating wood, which consists in producing around thewood while in a retort, a body of free steam under pressure and thentransferring the wood while covered, from said retort, into anequalizing chamber and then subjecting the wood to dry heat whileremoving the accumulating moisture from the equalizing chamber.

7. The process of treating wood, which consists in producing around thewood while in a retort, a body of free steam under pressure, and thentransferringthe wood from, said retort'into an equalizing chamber andthen subjecting the wood to dry heat while removing the accumulatingmoisture from the equalizing chamber, the treatment being carried outwhile the wood isunder mechanical pressure. a

'- 8; The process of dryingjlu'mber, which consists in subjecting thelumber to a body of live steam under pressure while simultaneouslyapplying dryheat, then transferring the lumber and while in transitpreventing the escape 'of heat, and then subjecting the lumber to dryingheat while periodically removing the accumulating moisture. I

- In testimony whereof I affix my signature.

- FREDERICK K; FISH JR.

